Waters must be disinfected before treated with reverse osmosis (RO) membranes in order to minimize biofouling. However, this leads to the formation of potentially harmful disinfection by-products (DBPs). The fate of the DBPs during membrane treatment may be impacted by operational changes such as temperature, water flux, and pH. In order to better understand this, aqueous solutions containing a mixture of DBPs (trihalomethanes, haloacetonitriles, haloacetic acids, cyanogen halides, haloketones, and chloropicrin) were circulated through a cross-flow bench scale system installed with an ESPA 2 membrane. DBP rejection over time was monitored and operational parameters were systematically altered after rejection at the membrane surface was stabilized. Generally, DBP rejection was higher with increasing water flux and decreasing temperature while being unaffected by changes in pH. Haloacetic acids were not affected by any of these operational manipulations but were well rejected (>90%). Cyanogen halides appeared to be particularly sensitive to concentration polarization as indicated by negative rejections, the lack of change in rejection with water flux, and decreased rejection at a lower temperature (10�  C). They also were rejected more at higher pH, potentially due to changes in effective 'pore' size. This research indicates which mechanisms may be responsible for the rejection of DBPs by RO membranes and has important implications on the application of membrane filtration in water treatment.

Impact of operational parameters on the fate of disinfection by-products during reverse-osmosis membrane filtration

248th National Meeting (2014)

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